The invention concerns a weighing device for the continuous determination of the weight per unit area of fiber material running as a band or as matting, which is delivered out of a preceding machine or from a fiber material container to the weighing device. The material leaves the weighing device to enter a subsequent fiber working machine or fiber material storage facility.
Weighing apparatuses of this kind, as they, are known in the art, show great variation in design. The fiber material is conducted on an essentially horizontal transport belt, beneath which the weighing apparatus is placed. In EP 0 635 589 A1 an electronic belt weigher is described, which precedes the intake apparatus of a carding machine or the like. The fiber mat resulting therefrom is discharged onto an endless, running belt leading to the intake apparatus of the carding machine. In the midsection of this running belt, which carries the fiber mat, is located a measurement device. This measurement device determines the weight of the fiber mat on a given weighing stretch. By use of a xe2x80x9cset-point vs. actualxe2x80x9d comparison, the belt speed, which is the mat velocity, is controlled so that added spinning material matches a desired weight per unit area or band weight of the finished product. The set value for the surface or fiber band weight can relate itself to the output of one of successive fiber processing machines. One of these machines can be for instance, a matting band layering machine.
This type of band-weight determination is prone to error in that the loading of the weighing device under the transport belt is affected by the elasticity and the tension of the belt as it transports the fiber band.
In order to avoid this fault and to render the weighing apparatus independent of the feed and removal of the material to be weighed, patent number DE 39 13 733 A1 proposes to make the support belt with the weighing device independent from the feed table. The patent attempts to do this in such a manner that the support belt with its drive apparatus along with the spinning goods carried thereon is weighed. Upon subtraction of the tare, the weight of the spinning goods can be determined. Following the weighing belt, but independent thereof, is a subsequent feed table for the next machine.
Experience has shown that this arrangement is not satisfactory. One reason is that upon the transport of fiber mass in the form of a precompressed matting or band, bridge formations appear at the transitions between the transport belt of the feed table and the weighing belt as well as at the subsequent transport belt. This bridge formation has the effect of giving support to the fiber mass in the transition zone at the neighboring transport element. The results of the measurement are falsified in that the fiber mass which is on the transport belt can support itself by its own fiber friction and clinging characteristics at these transition points of the incoming or outgoing fiber mats. Therefore, the entire true weight does not react on the weighing apparatus.
A further factor influencing weight determination with known weighing apparatuses at transition points between the incoming and outgoing fiber mats to and from the weighing belt is the uniformity of the material which is found in this zone. If the material which is to be weighed between these transition points has the same density, then an effective weight reference necessary to match the actual length of the weighing belt can be determined by a series of measurements. However, if the material is not uniform within the transition points, then the weight which is recorded as a ratio of the length of the laid down material on the weighing belt to the reference length also changes. Placing a correction on the inconsistence of uniformity in the case of known weighing apparatuses is not possible since a constant feed drive control for the feed of material is only workable with uniform material.
The purpose of the present invention is to create a band or matting weighing device which avoids the disadvantage of the formation of bridging and the weighing errors caused by this formation.
Objects and advantages of the invention will be set forth in part in the following description or may be obvious from the description, or may be learned through practice of the invention.
One exemplary embodiment of the present invention provides for a weighing device for the determination of weight of a fiber material. The weighing device includes two weighing arms, each of which are pivotably supported on one end. Each of the weighing arms are supported on an opposite end by a weighing element. The weighing arms are configured for supporting and transporting the fiber material. The weighing element provides a signal for the determination of the weight of the fiber material.
The present invention also encompasses a weighing device used for the continuous determination of weight per unit area:of fiber material. The weighing device is located downstream from a fiber working machine or a fiber material container that transports the fiber material to the weighing device. Also, the weighing device is located upstream from a fiber working machine or a fiber material storage apparatus to which fiber material is transported from the weighing device. The weighing devices includes two weighing arms that are both rotationally supported on one end by an axle. A feed apparatus is present and is located proximate to the rotationally supported end of one of the weighing devices. Also included is a removal apparatus that is located proximate to the rotationally supported end of another of the weighing arms. A weighing element is present which supports the end of the weighing arms opposite from the end of the weighing arms that are rotationally supported.
Another exemplary embodiment of the present invention exists in a process for the continuous determination of the surface weight of fiber material. The process includes the step of transporting the fiber material over two weighing arms which are supported by a weighing element on the two ends of the weighing arms that are proximate to one another. The process also includes the step of determining the weight that is lying on each of the weighing arms. Further, the process includes the step of the determination of the surface weight by taking the arithmetical average of the two measured values.
The present invention also encompasses the weighing device as discussed above where each of the weighing arms has a separate weighing element supporting the ends of the weighing arms.
Additionally, the present invention also includes an exemplary embodiment of a weighing device as discussed above which further has a transport belt located on the weighing arms. The transport belt accepts the fiber material from the feed apparatus and transports the fiber material to the removal apparatus.
Alternatively, the present invention includes an exemplary embodiment of a weighing device as discussed above where each of the weighing arms has a transport belt for transporting the fiber material and each of the transport belts has a turn-around roll. The weighing arms are rotatable about each respective turn-around roll.
Also provided according to the present invention is a weighing device as discussed above which further has a compensating balance on each of the weighing arms to counterbalance the weight of the weighing arms.
A further exemplary embodiment of the present invention exists in a weighing device as immediately discussed where the compensating balance has a compensation weight. The compensation weight is located thereon in order to compensate for the weight of the weighing arms.
Additionally, the present invention includes an exemplary embodiment of a weighing device as previously discussed where the axle is a stationary knife edge support.